1. Field of Invention
This disclosure is in the field of apparatus and related methods for facilitating the application of a cutting tool to a work-piece rotating on the axis of a lathe.
2. Background of the Invention
Lathes are tools which, among other things, spin a block of material around an axis of rotation. Frequently, tools are applied to the spinning material, i.e., work-piece, to perform various operations such as cutting, sanding, knurling, drilling, or deformation to create an object which has symmetry about the axis of rotation. Just as frequently, it is necessary to use the lathe and tool to create complex geometric shapes on the work-piece. For example, it is often necessary to create concave grooves, convex bulges, spherical facing, and tapering on a work-piece. Application of the tool to the work-piece by hand alone can be unsteady and may result in irretrievably inaccurate or unacceptable modifications of the work-piece and its associated geometric shape. Accordingly, apparatus and related methods were developed which facilitate the application of a tool to the work-piece of a lathe, including a means to guide taper, concave and convex radius, and tangential turn cutting operations. Such apparatus have heretofore been known as lathe tool-rests or lathe tool-holders.
Initially, lathe tool-rests were equipped with slide mechanisms (U.S. Pat. class code 82/137) for providing the tool-rest with heave and sway moveability (i.e., translational displacement), usually with respect to the lathe work-piece. The identified movement has heretofore been accomplished via: sliding the tool-rest along a dovetail and gib (see, e.g., U.S. Pat. No. 91,215 (issued Jan. 15, 1869)); or movement by lead screw mechanisms (see, e.g., U.S. Pat. No. 143,080 (issued Sep. 23, 1873)). Although an improvement over hand-held tool applications, heave or sway movements, by themselves, have not been completely satisfactory for use in connection with shaping a work-piece on a lathe. In particular, the limitation of only two translational degrees of freedom, as is the case for heave and sway tool-rests, restricts complex tapering or the creation of convex or concave geometries because, among other reasons: (1) the tool-holder must consistently be repositioned with respect to the work piece in order to provide directional tapers; and, (2) radial cuts or tapers, including concave or convex radial cuts, cannot be easily made since it would require simultaneous and accurate sway and heave tool movements. For these reasons, among others, further improved lathe tool-rests/holders were developed to facilitate the application of a tool to the work-piece of a lathe.
One advancement in lathe tool-rest apparatus involved the incorporation of a pivot (U.S. Pat. class code 82/12), in addition to slide mechanisms, whereby orientation of the heave and/or sway tool-rest movements may be readily set, and/or whereby yawing movements may be accomplished by the tool-rest (i.e., concave and convex radial cutting). For example: U.S. Pat. No. 55,749 (issued Jun. 19, 1866) generally discloses a tool-rest with a pivot “C” positioned proximate to a work-piece whereby a tool “F” may be rotated to make a convex spherical cut on the work-piece (see also U.S. Pat. No. 94,930 (issued Sep. 14, 1869) (tool “M” and pivot “i”), U.S. Pat. No. 670,962 (issued Apr. 1, 1901) (tool “a′” and pivot “C”), U.S. Pat. No. 923,757 (issued Jun. 1, 1909) (tool “46” and pivot “19”), U.S. Pat. No. 1,201,004 (issued Oct. 10, 1916) (tool “6” and pivot “19”), U.S. Pat. No. 1,556,949 (issued Oct. 13, 1925) (tool “16” and pivot “37”), U.S. Pat. No. 1,626,936 (issued May 3, 1927) (tool “17” and pivot beneath axis of rotation “35”), U.S. Pat. No. 2,295,014 (issued Sep. 8, 1942) (tool “43” and pivot “48”), U.S. Pat. No. 2,460,342 (issued Feb. 1, 1949) (tool “26” and pivot “11”), U.S. Pat. No. 2,828,658 (issued Apr. 1, 1958) (tool “14” and pivot “18”), U.S. Pat. No. 3,064,510 (issued Nov. 20, 1962) (tool “25” and pivot “B”), U.S. Pat. No. 3,447,245 (issued Jun. 3, 1969) (tool “35” and pivot “47”), U.S. Pat. No. 3,345,893 (issued Oct. 10, 1967) (tool “35” and pivot “47”), and, U.S. Pat. No. 5,566,597 (issued Oct. 22, 1996) (tool “9” and pivot “11”)); and, U.S. Pat. No. 637,769 (issued Nov. 28, 1899) generally discloses a sliding tool rest “D” placed on a “axially-pivoted swivel C” which is movably secured to a lathe carriage for cutting concave radial cuts (see also U.S. Pat. No. 759,083 (issued May 3, 1904) (tool “B” pivot “f”), U.S. Pat. No. 867,798 (issued Oct. 8, 1907) (tool “14” and pivot “6”), U.S. Pat. No. 2,295,014 (issued Sep. 8, 1942) (tool “46” and pivot “62”), U.S. Pat. No. 2,435,212 (issued Feb. 3, 1948) (tool “23” and pivot “11”), U.S. Pat. No. 2,450,469 (issued Oct. 5, 1948) (tool “23” and pivot “24”), U.S. Pat. No. 2,467,070 (issued Apr. 12, 1949) (tool “23” and pivot “3”), U.S. Pat. No. 2,529,551 (issued Nov. 14, 1950) (tool “34” and pivot “40”), U.S. Pat. No. 2,703,032 (issued Mar. 1, 1955) (tool “25” and pivot “19”), U.S. Pat. No. 3,447,245 (issued Jun. 3, 1969) (FIG. 2, tool “35” and pivot “47”), U.S. Pat. No. 3,345,893 (issued Oct. 10, 1967) (FIG. 2, tool “35” and pivot “47”), and U.S. Pat. No. 4,750,392 (issued Jun. 14, 1988) (tool “38 and pivot “40”)). Although better than tool-rests with only sliding mechanisms, there is room for improvement in tool-rests with pivot and sliding mechanisms. Consider the following drawbacks, among others not specifically recited. First, the above-disclosed apparatus are complex in terms of operation whereby many tool rest components must be set and adjusted prior to making even a single cut. Notably, many of the moving parts cannot easily be manipulated simultaneously, if simultaneously manipulable at all. Second, the above disclosed tool-rests must be uninstalled and reinstalled at different locations along the work piece, or used in conjunction with a particular type of lathe to complete a full spherical or radial cut or otherwise shape the entire work-piece. This drawback is particularly offensive since timely repositioning of the tool-rests' carriage is often involved. Third, many of the above disclosed embodiments are inefficiently designed whereby excessive amounts of materials are required for tool-rest fabrication. Fourth, many of the subject tool-rests restrict the initial size of the work-piece since, the tool-rests feature non-cutting components that are in close proximity to a lathe's axis of rotation. Fifth, the above cited devices are designed for making radial cuts and do not also effectively cut tapers. Sixth, a primary drawback of the above-disclosed tool-rests is the absence of an operable secondary pivot point for enabling compound radius turning or tapering operations (i.e., the application of a tool to a work piece via manipulating a second operable pivot point in addition to rotation of the tool around the primary pivot and/or linear movements of the tool). The identified lack of an operable secondary pivot point restricts the types of geometries capable of being cut by the tool-rest and prevents the use of a roulette motion to control precise radial tool path and orientation along the desired work piece cuts. Accordingly there is a need for a tool rest that avoids the drawbacks identified above.
Apparatus are further known which may have a secondary pivot. For example, U.S. Pat. No. 684,508 (issued Oct. 15, 1901) discloses a tool-rest featuring a primary pivot, “H,” wherein a second pivot may be at the tool-prop, “D.” However the pivot at prop “D” is not completely operable since the prop “D” is not movable to cut or shape a work-piece. Rather, the prop “D” is secured in a particular orientation for guiding a hand-held tool, whereby reorientation of the prop “D” and cutting the work-piece require separate and time consuming steps. Furthermore, the prop “D” is not operable in that smooth and workable rotation cannot be accomplished since the prop “D” must be locked in position via a clamp “C” prior to cutting the work piece. In other words, the apparatus cannot be used for compound radius or tapering operations since the apparatus cannot accomplish the application of a tool to a work piece via manipulating a second pivot point in addition to rotation of the tool around the primary pivot and/or linear movements of the tool. For another example, U.S. Pat. No. 2,386,984 (issued Oct. 16, 1945) discloses a tool-rest featuring a first, “19,” and second, “25,” pivot. However, the second pivot “25” is not entirely operable since, the screw “26” must be loosened to enable pivoting, the pivot arc is restricted to only the path “27,” and the screw “28” must be turned in order to accomplish rotation around the pivot “25.” As above, the pivot “25” is not manipulable to accomplish cutting or tapering, but rather the cutting may only be accomplished via movement around the first pivot “19”. Specifically, the second pivot “25” is only for aligning the cut. In other words, reorientation of the tool via the second pivot 25 and actually cutting the work-piece require separate and time consuming steps. Thus, the disclosed apparatus cannot be used to make compound radial or tapering cuts. In addition, the identified lack of an operable secondary pivot point restricts the types of geometries capable of being cut by the tool and prevents the use of a roulette motion to control precise radial tool path and orientation along the desired work piece cuts. Finally, for yet a further example, U.S. Pat. No. 2,716,913 (issued Sep. 6, 1955) and U.S. Pat. No. 4,497,144 (issued Feb. 5, 1985) disclose cutters with multiple pivot points. However, the multiple pivot points do not amount to separate and operable pivots since they are not independent from one another and all pivots must be moved in concert to accomplish a particular cut. Furthermore, all of the heretofore disclosed tool-rests are composed of excessive moving parts whereby the strength and integrity of the tool may be easily compromised and whereby construction and fabrication of the tool-holders are overly complex and expensive. In addition, most of the identified examples feature the drawbacks as identified in the preceding paragraph. Accordingly, there is a need for a lathe tool-holder having separate and independently operable pivots for facilitating the application of a tool to a work piece and that may further be used for making compound radial or tapering cuts.